The invention relates to a control device for a vehicle motor.
There exists a control device for a vehicle motor that includes a torque-controlling device that controls a torque of the vehicle motor, and of stall-detecting device that detects a stalled state of the vehicle. When the stall-detecting device detects a stalled state of the vehicle, the torque-controlling device controls the motor so as to reduce the torque.
According to an example of such a control device, the torque of a traction motor is reduced upon detecting the stalled state of the vehicle such that a speed or an acceleration of a backward movement of the vehicle is less than of equal to a predetermined speed. Furthermore, an allowed time during which the vehicle remains stalled is set based on the torque applied to the traction motor, and the torque is reduced when the stalled time exceeds the allowed time (See, for example, Japanese Unexamined Patent Application Publication No. 7-336807 (paragraph numbers 0015 to 0021, FIG. 1)). Accordingly, the vehicle moves backward due to the torque-reducing control, and a rotor of the motor is rotated based on the torque reducing contact. Thus, the current-carrying phase is switched such that the current does not intensively flow in a particular phase.
Moreover, according to another example of the control device, when a motor 5 is determined to be locked or stalled (Steps S11, 12), a restrictive torque πr, depending on a maximum junction temperature TJMAX of a switching element of an inverter circuit, is calculated (Step S27). When the restrictive torque πr is less than an indicative torque πc of the motor and the phase range is equal to the previous state, a limited torque TL is reduced by a displacement torque Δπ by subtracting Δπ from the restrictive torque πr (Steps S29 to S37). Accordingly, the phase range is changed so as to release the locked state (Japanese Unexamined Patent Application Publication No. 11-215687 (paragraph numbers 0020 to 0029, FIG. 2).